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Thu Jul 24 18:23:00 CEST 2008 · https://mail.python.org/pipermail/python-dev/2008-July/081533.html

Antoine Pitrou wrote:
> Thomas Lee <tom <at> vector-seven.com> writes:
>   
>> By the way, you were right about JUMP_IF_TRUE/JUMP_IF_FALSE. It's far 
>> too late. Apologies.
>>
>> I'm still pretty sure this is the peepholer's doing,
>>     
>
> Yes indeed.
>
>   
>> Which is what's being achieved with the AST optimization I originally 
>> proposed, right?
>>     
>
> Well, not exactly, your optimization eliminates the UNARY_NOT by swapping the
> if/else blocks, while the peepholer eliminates the UNARY_NOT by fusing it with
> the subsequent jump opcode. In this case it doesn't make much of a difference,
> but if there is only an "if" without an "else", the peepholer's optimization is
> still possible while yours is not.
>
>   

Unless a pass is injected into the if body, which will generate no 
additional bytecode and still have the same net effect.

> (bottom line: the peepholer is not dead!)
>
>   
We'll see ;)

Thanks for all your help, I'm looking forward to getting my hands on 
that patch.

Cheers,
T

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[Python-Dev] lnotab and the AST optimizer